Impact of land management on soil macrofauna in the ...

Eiw. J. Soil Bid., 1994, 30 (4), 157-168

- 1 1

Impact of land management on soil macrofauna in the Oriental Llanos of Colombia T. Decaëns (‘1 ($1 (‘1, P. Lavelle ( l ) ,J. J. Jiineiiez Jaen (2), G. Escobar (3) aiid G. Rippstein

”’ O.RS.T.O.Al.,

Laborafoirr di!?cologie des Sols Trojicaux, 72, roiifr dXuhiay, 93143 Bondy Cedt.’Y, Fra,ice. L h i m s i d a d Comnjiliifunse. DeFeirtntiienfo dt?Biologia iiiiinial 1,Fuciilfati dr Biologia, 28030 Madrid, Spain. l3) C.I.A. T., Cariiiiagua, Apui-fado 4h-oo hp 6713, Cali, Colonibiu. w Comesjioiidiizg.author ( ‘ I z i Acfual addms: Uniumsifé de Rourti, U.F.R Srieizres, Laboratoire d Ecologie, Flace Eitiilt Blondel. 76821 hlo?if SaìTit-Aigiian Cedex, Frailce.

Received April 9, 1994: accepted October 19, 1994.

Abstract

The effect of different types of land management on the soil macrofauna of the savanna has been assesed using the T.S.B.F. method. Macrofauna of the forest and savanna bas a high density (4293 and 2 830 ind. in-’) and moderate biomass (13.6 and 15.3 g . m-z). Traditional grazing significantly increase earthworm biomass but does not modify biomass (16.8 g . mLz)and density (1 971 ind. ni-?). Buming the savanna leads to a momentarily but important disruption of the soil fauna. After 6 months, soil macrofauna has regained its initial level. When stocking rate increase, contribution to biomass of different groups is modified. These results are probably due to the modification of the soil microclimate and to the imput of cow dung. Improved pastures have an important earthworm population (22.9 to 51.1 g. ni-’) composed of native species, and a high macrofauna diversity (26 to 32 units). This results from the improving of the quality of the organic matter brought to the soil (litter and cow dung). Annual high input cultivations results in a spectacular decrease, both quantitative and qualitative. in the invertebrate populations (3.2 to 4.3 g . m-2, 429 to 592 ind. ni-? and 18 units). This phenomenon may be explained by the effect of the tilling of the soil, the fertilization and by the decrease o f the soil organic matter. Keywords: Soil macrofauna, earthworms, biomass, density, taxonomic richness, savanna, gallery forest,

Colombia, land management. Impact de Ia gestion de Ia terre SUI- Ici ínaci-ofaime des sols dans les Llanos Orientau de Coloínbie.

Résume

L’impact de différents types d’utilisation de la terre sur la macrofaune du sol de la savane a été évalué en utilisant la méthode T.S.B.F. La macrofaune de la forPt et de la savane possPde une densité élevée (4293 et 2 830 ind. ni-2) et une biomasse moyenne (13,6 et 15,3 g . ni-?). L’utilisation traditionnelle de la savane provoque une augmentation significative de la biomasse de5 vers de terre mais ne modifie pas la biomasse (16.8 g.m-?) et la densité (1 971 ind. m-2). Le passage du feu entraîne une perturbation momentanée mais importante de la faune du sol. AprPs 6 mois. le sol a retrouvé une faune équivalente 2 celle qu’il possédait avant le feu. Si l’on augmente la charge animale, la contribution h la biomasse des différents groupes est modifiée. Ces résultats sont probablement liés B la modification du microclimat du sol et à l’apport de bouses de vaches. Les phrages améliorés abritent une importante population de vers de terre (22,9 h 5 1,1 g . m-’) composée d’espèces natives et une macrofame riche en taxons (26 B 32 unités). Ceci est le résultat de l’amélioration de la qualité de la matière organique apportée au sol (litière et bouses de vaches). Les cultures annuelles fortement fertilisées montrent une diminution spectaculaire, quantitative et qualitative, des populations d’invertébrés du sol (3,2 à 4,3 g. m-?, 429 à 592 ind. m-’ et 18 unités taxonomiques). Ce phénomène peut être expliqué par l’action du travail du sol, de la fertilisation et par la diminution de la matière organique du sol. Mots-cl& : Macrofaune du sol, vers de terre, biomasse, densité, richesse taxonomique, savane, forêt galerie, Colombie, gestion du sol.

T. Decaëns et al.

158

INTRODUCTION

hIATERIALS AND PcIETHODS

The Eastern Llanos of Colomhia are a broad area of savanna still poorly exploited through traditional cattle ranching. An intensification has recently been attempted in the most accessihle areas. Various techniques are tested such as management of natural pastures or improved pastures. rotations of culture and improved pastures. intensive cropping. The sustainability and impact on soil quality of these techniques are still poorly known (Fisher ct id.. 1992). The effect on soils of e.g.. the introduction of african ' grssses, sinipiification of the plant coniniunii\. or different levels of stocking rates are totally ignored. The accelerated degradation of large areas of pastures in Amazonia putb ecologists in fear that the systems under study are neither sustainable nor conservati\ e in biodiversity.

Characteristics of the study area

Aniong the ~iumeroiis factors that determine the quality of soils. biological regulations. operated by soil niacroorganisms (living roots and macroinvertehrates) niay be determinant (Lavelle C t (11.. 1994). These systems play a key role in the conservation of soil fertility since they affect the phqrsical and chemical properties of the soil. organic nutter arid nutrient cycling and plant growth (Lavelle ct d.. 1994: Stork and Eggleton. 1991). Macroinvertebrates ha\ e different effects on the processes that determine soil fertility. They regulate microbial populations responsible for the niineralisation and humification processes and consequently influence organic matter cycling and the release of nutrients assimilable hy plants. Through their mechanical action on the soil. they contribute to the formation of stable aggregates \+hich ma! protect a part of soil organic matter from a fast mineralisution and therefore constitute a nutrient reserve potentially available for plants. klacroinvertebrates can modify texture and physical properties of the soil in the upper horizons that they inhahit (Lavelle t'f í i l . . 1994). Illacrofaunal activities ma)- also favour plant growth (Spain t'f ( i l . . 1992). Tlie diversity and abundance of macroin\-ertebrate communities itnd the relative importance of major groups such as termites. earthLvornis and ants can therefore be used as indicators of soil quality (Stork und Eggleton. 1991).

The present study has been carried out at the research station of Carimagua iC1AT-IC.4). Special attention wv;is paid at testing the effect of a large variety of pasture management practices such as burning of the native savanna. introduction of african grasses ( R n i d i i i r r i t r tlcc-rnrrhcns,, and improvement with legumes ( P w n i r i ~I7/itrscc,l~7irlt'.s). i and different stocking rates. On the other hand. \ve tried to test the assumption that pastures create "green deserts" d i e n installed :ìt the expense of native forests or \:{vannas.

The research \tation of Cariniagua (4'30'N. 7'30' W ) is located in the phytogeographic unit of the "Altillanura Plana". In this area. \ egetation comprises well drained sa\ anna\ in the upland areas ("altos" and "planos") and gallery forest\ in the lowlying areab I"ba~ios-7. The climate is whhumid tropical with an annual mean temperature of 26°C and precipitation5 of 2300 mm (C1AT.s data. means of the ]ears 19711992). Two beasons can be ohsenrd i.e., a dry seawn it ith ;I\ erage monthl) precipitation:, of less than 100 mm. from December to March, and a wet beason with a\ erage monthly precipitation5 greater than 100 mni. from April to November. Two types of soil can be found in the area of Carimaguri i.r.. O\isols (Tropeptic Haplustox Isohyperthermic) in the "altos" and "planos" and Ultisols (Ultic Aeric Plintaquo\) in the "ba.jos". They have good ph] \ical properties (porosity. mater retention) but prebent a great chemical povertj (CECer also lind been recolonized and comprised SOr; of the popu1,it'ion. hJ;rc.roin\-ertrhratc cnmniunities of improved pastures [vere characterized by a high biomass and ta\;ononiic riclines3 and it medium population density. Earthvarnis largely dominate ;is they comprised goci, ot' the overall hiomah?; (,fie. 2. t and two nati\ e :,;i\-;inn:i species. i.. Burning the savanna seeins to directly destroy ;I large p:irt of the \oil macrofauna. Populution denhity. binmass and ta.tononiic riclines5 clearl> decreased and termites seemed to be the most benciti\-e group (.fi.?. 6,. Fire a l h o :iffected the distribution in dcpth hui J. 5cid l3iol

Table 3.

- Density

(n .d)and biomass ( g . m-')

of soil macrofauna and earthworms in various studied sites. Earthworms

Macrofauna Locality

Vegetation type

Biomass

Density

Biomass

Density

Reference

Colombia Côte d'Ivoire Nigeria Mexico

Gallery forest Tropical forest Tropical forest Tropical forest

13.6 74.2 16.4 16.4-18.9

4 294 5 747 3 119 888-3 01 1

4.7 52.3 10.2 9.8-10.7

251 171.2 34 8-132

This study Gilot et al., in press Madge, 1969 Lavelle and Kohlmann, 1984 1981 Lavelle et d.,

Tropical forest Tropical forest Temperate beechwood Savanna Savanna

24.1-53.9 2.4-6.8 12.7 15.3 29.7-84.8

4 099-4 303 663-2 579 4 035 1830 2015-10905

11.9-28.2 0.4-1 10.7

85-120 24-42 205

Lavelle and Pashanasi, 1989 Collins, 1980 Schaefer, 1990

4.8 17-48.6

157 188-400

Colombia Peru

Traditional pasture Traditional pasture

8-16.8 82.3-121.2

698-2 029 1 768-2 347

Colombia PeN Mexico India

Improved pasture Improved pasture Improved pasture Improved pasture

28.8-62.5 110.9-159.2 -

1541-2267 922-1 546 -

-

4.5-1 3.8 78-116.4 22.9-51.1 103.2-153 35.8-55.5 30.2-56

32-1 92 474-573 139-2 13 546-740 620-948 17.4-800

This study Lavelle, 1983 Lavelle et al., 1992 This study Lavelle and Pashanasi, 1989

Colombia Peru

High input crops High input crops

3.2-4.3 3.1

429-592 730

0.5-2.3 1.5

18-27 14

Peru SGlWak Germany Colombia Côte d'Ivoire

This study Lavelle and Pashanasi, 1989 Lavelle et ul., 1981 Dash and Patra, 1977 Sepanati, 1980 This study Lavelle and Pashanasi, 1989

T. Decaëns et al.

166

of the community since 15 dal-s after burning. the 0- 1 0 cm layer only comprised 3 5 4 of the invertebrates (.fig. 4). Macrofiiuna quickly regenerated and. after 6 months, had recovered its initial biomass, density and taxononiic diversity ahile the 0- I O cm layer has been recolonized. These observations are in contradiction \vit11 the results of Athias ct d.(1975) in C6te d'Ivoire. that indicate a delayed effect of hurning whereas no immediate effect has been observed. The difference betaeen both situations may result from the timing of burning. Fires studied in Còte d'Ivoire had been set during the dry season when large part of fauna is already adapted to the stress linked to drought. and remites are nor affected by hurning since rhey íive either deep in the soil or in surface mounds with thick ~valls(losens. 19731. At Cariniagua. no preadaptation to the stress brought about by fire seems to exist. Overgrazing does not affect biomass and population density but reduces taxonomic richness. The increase of the stocking rate reduces the relative importance of earthworms (only 33.4% of biomass in the most highly grazed plot) (.fi\?. 6). This can be due to a modification of soil microclimate induced by the reduction of the herbaceous vegetation. Coleoptera are iibundant in the most higlily grazed plots (.fig. 5 ) (7.1'4- of biomass in the medium and 24% in the high stocking rate) but remains less important than in hlesican p;ist'ures ( 2 5 to 48 g . ni-:) (Villahos and Lawlle, 1990).The increased inputs of cmv-dung to the soil probably explain this ch ange. Microfauna communities in improved pastures have a medium population density. and ;ihigh biomass and taxonomic richness. although bioniasb remains inferior to that measured in other tropical pastures. Native earthivornis of the savannfi are the major component of biomass ( SO% 1 with absolute value.; of 22.9 to 5 1 . 1 g . mM2.equivalent to other improved pastures in hlexico or India hut still inferior to Peruvian pastures Ctiildc 3 ). This increkise of biomass is certainly due to the improvement of the quality of the litter brought to the soil in the form of cowdung and legume leaf and root litter. Addition of legumine l e x e s rich i n nitrogen. in the case of E. tlearmhcws + Kutlzu pasture. niaintainr taxonomic richness and increases biomass to v a l u e ~4 times higher thut in the protected savanna. Contrar!. to pastures established on ;i forest precedent, natiw niacrofaunx communities seem to be favoured b!- the iniprovement of trophic conditions and there is no proliferation of exotic species of earth\f,orms like in man) tropical pastures (Liivellc ct 111.. 19s 1 : Lnvelle :ind Pabhanasi. 1989 t. Other groups o f some importance are Isop~~da. indic:itnrs of a humid \oil niicrocliriiate. and Coleoptera. certainly fitvoured b! the input of' co\\wlung and incwased root biomass (.fia. 5 I . High input cropping rewlts in :i dramatic decrease of taxonomic richne?;\. population den\it>

and biomass. These results confirm other obw-1atinns made in Peru (tuhle 3 ) and can be explained by the negatil e action of soil tillage. ferrilibation (ebpeciallj \%hen i t induces an acidification of the soil). modification of the soil microclimate. non-txget effects of pebticides and decrease of the reserVes of carbon available in the soil as a result of the destruction of the perenial \ egetation (House and Parmelee. 19x5; Reddy and Goud. 1957).

CONCLUSION In general. niacroimertebrate populations clearly respond to perturbations induced by soil mnnagement. The traditional exploitation of the savanna as natural pastures has little influence on soil fmna :ind rccolonisation of soil after fire is fast. Earthu.ornis arc favoured by grazing and fire but their importancc decreases Lvith overgruzing. Termites respond in clearly opposite manners and the ratio of earthwormsltermites may be considered as a sensitive indicator of the state of the environment. Sorving inipro\-ed fodder plants and increasing animal production in improved pstures has :i wry important impact on soil macrofauna. especially on earthLvorm populations which increase their biomass from 4.S to up to 51.1 g.ni-'. The association of B. tJe~wihcris + Kudzu seems to be of high value regarding the conservation of soil quality and biodiversity since it also maintains savanna taxonomic richness. The improvement of leaf litter quality and the great quantity of cmv-dung brought to the soil can explain these resulta. Establishing improved pastures on a natural savmna does not transform the medium into ;I "green desert" but. t o the contrary. increases the activity of local mucmfrtun:i comiiiunities. Annual5 crops have a dramatic effect on earthLvorms and arthropod populations. Lvith ;i spectacular decresse of biomass. population density and taxonomic richness. The factors respon5ible for this phenomenon can he found in agricu1tur:il practices such as tillage. fertilisation or application of pesticides. in the reduction of root production and the niodification of the soil micrcxlimate occuring after the clearing the natural vegetation. Il1:icrof:iuna of tropical soils seeins to be a wry sensitive factor. but further research is needed to understand the dynamics of populations experiencing in;ìjor disturbances m d processe$ of recolnni.;;ition by macrof:iuna in regenersting environments. This cvill allow to design practices which allow ;i better conservation or the development of mxrofaiina and indicate.; n-a) s to \timulate the activities of existing fiiuii:~ soils or introduce better adapted species ti) restore soil fertility. Fur. J. S i d 81\11

Soil macrofauna in the Oriental Llanos of Colombia

167

Acknowledgements

We are grateful to the workers from the “Savana Nativa” program (CIATDEMVT) and from other programs of the Carimagua station for their help on the field, J.P. Rossi (ORSTOM) for statistical analysis. We alsow wish to thank Rainer Hermann for the time he had spen to help us to complete this research after his own work.

REFERENCES Anderson J. M. and Ingram J. (Eds.) (1993). - Tropical Soil Biology and fertility. A handbook of Methods, 2nd edition, Oxford: C.A.B.. 221 p. Athias F., Josens G. and Lavelle P. (1975). - Influence du feu de brousse annuel sur le peuplement eiidogé de la savane de Lamto. In: Vanck, J. (Ed.). Progress in Soil Biology, Prague, 389-396. Collins N. M. (1980). - The distribution of soil Macrofauna on the West Ridge of Gunung (Mount) Mulu, Sarawak, Ecologia, 44, 263-275. Dash M. C. and Patra U. C. (1977). - Density, biomass and energy budget of tropical earthworm population from a grassland site in Orissa, India. Rev. Ecol, Biol. Sol., 14, 46 1-471. Fischer M. J., Lascano C. E., Vera R. R. and Rippstein G. (1992). - Intergrading the native savanna ressource with improved pastures. In: CIAT, Pastures for tropical lowlands. CIAT’s contribution, Cali: CIAT, 238 p. Fragoso C. and Lavelle P. (1992). -Earthworm communities of tropical rain forests. Soil Biol. Biochein., 24, 1397-1408. Gilot C., Lavelle P., Keli J., Kouassi P. and Guillaume G. Biological activity of soil under rubber plantation in CBte d‘Ivoire. Eur. J. Soil Biol, In press. House G. J. and Parmelee R. W. (1985). - Comparison of soil arthropods and earthworms from conventional and no-tillage agroecosystems. Soil and Tillage Research, 5, 35 1-360. James S. W. (1988). - The postfire environment and earthworm populations in tallgrass prairie. Ecology, 69, 476-483. Josens G. (1972). - Études biologiques et écologiques des ternlites (Isoptera) de la savane de Lamto-Pakobo (Côte d’Ivoire). Thèse de Doctorat, Université Libre de Bruxelles. Lavelle P. (1983). - Chapter 21. The soil fauna of tropical savannas. I. The community structure. In: Bourlière F. (Ed.). 7kopical Savannas, Amsterdam: E.S.P.C., 477-484. Lavelle P. (1983 b.). - Chapter 22. The soil faum of tropical savannas. II. The earthwoims. In: Bourlière F. (Ed.). Tropical Savannas,Amsterdam: E.S.P.C., 485-504. Lavelle P. and Kohlmann B. (1984). - Étude quantitative de la macrofaune du sol dans un forêt tropicale du Mexique ( Bonampak, Chiapas). Pedobiologia, 27, 377-393. Lavelle P., Maury M. E. and Serrano V. (1981). - Estudio cuantitativo de la fauna del suelo en la region de Laguna Verde, Vera Cruz. Epoca de Lluvias. Inst. Ecol. Publ., 6, 75- 105. Lavelle P. and Pashaiyasi B. (1989). - Soil macrofauna and land management in Peruvian Amazonia (Yurimaguas, Loreto). Pedobilogia. 33, 283-29 1. Vol. 30, no 4

-

1994

Lavelle P., Dangerfield M., Fragoso C., Eschenbrenner V., Lopez D., Pashanasi B. and Brussard L. (1994). Chapter 6. The relationship between soil macrofauna and tropical soil fertility. In: Noomer P. L. and Swift M. J. (Eds.). The iiianagerizent of the Tropical Soil Biology and Fertility, Wiley-Sayce Publication. Madge D. S. (1969). - Field and laboratory studies on the activities of two species of tropical earthworms. Pedobiologia, 9, 188-214. Reddy M. V. and Goud A. N. (1987). - Impact of inorganic fertilizers on the earthworm population density of wetland rice (Oiyia sativa) agroecosystems. Proc. Nat. Syinpos. Ecotosic., 154-158. Senapati B. K. (1980). - Aspects of Ecophysiological Studies 011Tropical Eartlz~voi-las.Distribution, Population Dynamics, Production, Energetics, and their Role in Decomposing Process. Thesis, Sambalpur University, Sambalpur, 154 p. Schaefer M. (1990). - The soil fauna of a beech forest on limestone: trophic structure and energy budget. Ecologia, 82, 128-136. Spain A. V., Lavelle P. and Mariotti A. (1992). -Stimulation of plant growth by tropical earthworms. Soil Biol. Biochenz., 24, 1629-1633. Stork N. E. and Eggleton P. (1992). - Invertebrates as determinants and indicators of soil quality. American J. Alternative Agriculture, 7, 38-55. Thioulouse J. (1989). - Statistical analysis and graphical display of multivariate data on the macintosh. Computer Applications in the Biosciences, 5, 287-292. Thioulouse J. (1990). - MacMul and GraphMu: two Macintosh programs for the display and analysis of multivariate data. Computers and Geosciences, 16, 12351240. Villalobos F. J. and Lavelle P. (1990). - The soil coleoptera community of a tropical grassland from Laguna Verde, Veracruz (Mexico). Rev. Ecol. Biol. Sol, 27, 73-93.

APPENDIX List of the taxononlic units collected in the soil during the sampling period Taxonomic units EARTHWORMS Glossoscolecidae Megascolecoidea (Acanthodrilidae and/or Ocnerodrilidae)

Sites I, II, III, IV, v , VI, VII, VIU, M, I, II, v, VI, VI1

x

168

ISOPTERA Rhinothermitidse Trrniitidae Kaloterniitidae HYhIEN0PTER.A Formiciciae Othcrs COLEOPTERA Crirahi dar

T. DecaEns et al.

I. II. 111, IV. VIII. Ir;. N I. VIT I

v. VI. VII.

1. II. III. IV. v. VI. L'TI, VIII. IS.N I. II. v. VI. VI11

Opisthospermophora Sccdopendromorpha Others Pol ydesmida NEhI ATO D A

I. II. III. I\'. i'. \.I. VII, VIII. IS.x 1. II. v. VI11 11. VI11

HOhlOPTERA Cercopidat. Cicadidae Ci cadeIl idae HEnI IPTER 1 Other4 Corimelaenidae Redu\ idae C) dnidae ORTHOPTERA B 1attidae Grj llotalpinae Grj llinae hlantidae LEPIDOPTERA EhlBIOPTER4 C R USTACEX 14npndn THYS.L\NURA Lepiw"ar DI PTERX DER h I A PTE R '4 hlOLLLlSC.L\ Helicid:ie Limacidar DIPLURX

Scarahaeidae Chr) somelidae Staphylinidrie Curculionidae Tenebrionidae Lamp) ridai Others A 1lecu1i dae Scaphidiidae Pselqiiidae Cicindelidae Euct eri dae Cla\ igeridae SJ IphiJae Leiodidae Pa\\alidac. B! rrhidae Coccinelidar ARACHNIDA Araneida Acarina Phalangida

Che1nnethid:i hIYRIXPOD.4 Geophi1omorph;i

1. II

I. II. III. IV. v. VI. VII. VI11 I. III. V. VII. VIII, IX. x I. 11. IV. v. VI. VIII. Ix v. VI, VITI. IS.x I. II. VITI. I S I. II. IV, v. VI. VII. VITI. IX. x VII. \?III. IX I. IV. V. N II. 1x

I. II. IV. VI. VI1 I. II. IX II.

\l,

VI. VI1

1. II. Y. VIII. 1x' IV. VI1

TX IX I. IV. VIT, IS I, V I. Il, WII. IN II I. II. VI, VIII. IX. X I I. VIII. IX

IN I